1. Field of the Invention
The field of the present invention relates to internal combustion engines used with push lawnmowers, lawn and garden implements, or in small utility vehicles such as riding lawnmowers, lawn tractors and the like. In particular, the invention relates to an oil fill tube attached to the engine housing in fluid communication with the oil sump of the engine.
2. Description of the Related Art
Known internal combustion engines often include a rigid oil fill tube which is attached by a fitting to the engine crankcase in fluid communication with an oil sump contained within the engine crankcase, with the upper end of the oil fill tube attached to a bracket mounted on the engine shroud or blower housing. In order to fill oil into the crankcase, a cap on the upper end of the oil fill tube is removed and oil is poured through the oil fill tube into the oil sump.
The engine shroud is attached to the engine crankcase and is made from a thin, flexible stamped metal or a flexible plastic. A problem is that, during the running of the engine, flexing of the shroud allows substantial relative vibration to occur between the crankcase and the shroud, which is often transmitted through the rigid oil fill tube, eventually causing the fitting which connects the oil fill tube to the crankcase to fail, causing oil to leak from the oil sump though the fitting. This problem is exacerbated during running of the engine when the engine crankcase is pressurized by the reciprocation of the piston(s) therein, which forces oil through the failed fitting and out of the crankcase.
An additional disadvantage of this design is that engines of varying size necessitate oil tubes of varying lengths, such that an oil fill tube of a given size is only useful with a complementary sized engine. Problematically, different sized oil fill tubes must be separately manufactured for engines of varying size, which increases manufacturing costs.
The present invention provides an oil fill tube for an internal combustion engine which includes an engine housing containing an oil sump therein, the oil fill tube capable of flexing axially between first and second ends thereof, the first end of the oil fill tube sealingly attached to an oil fill hole in the engine housing in fluid communication with the oil sump, and the oil fill tube attached to an attachment member externally mounted on the engine housing.
The oil fill tube may include an accordion section having a plurality of flexible segment portions which enable the oil fill tube to be selectively flexed and bent into a variety of orientations, as well as allowing the oil fill tube to be extended and contracted between a variety of different lengths. Additionally, the oil fill tube may be attached to the engine housing via a variety of sealing, leak-resistant arrangements.
In a first such arrangement, the crankcase includes an oil fill hole with an adapter mounted therein, with an end of the oil fill tube threadingly attached to the adapter. In a second arrangement, the crankcase includes a boss defining an oil fill hole, with an end of the oil fill tube threadingly attached to the boss. In a third arrangement, the crankcase includes a boss defining an oil fill hole, and the oil fill tube includes a mounting flange spaced from an end thereof which is fastened to the boss with fasteners, with the end of the oil fill tube extending into the oil fill hole. In a fourth arrangement, the crankcase includes a boss defining an oil fill hole and having a first mounting flange, and the oil fill tube includes a second mounting flange spaced from an end thereof, with the first and second mounting flanges abutting one another and securely fastened together with a clamp with the end of the oil fill tube extending into the oil fill hole.
Advantageously, the oil fill tube may flex axially to isolate relative motion between the crankcase and the shroud, which flexing dampens the vibrations through the oil fill tube to reduce stress on the fitting between the oil fill tube and the crankcase. The oil fill tube may include a flexible, extendable and contractable accordion section having a plurality of segments which permit axial flexing of the oil fill tube. Additionally, each of the several fitting arrangements disclosed herein provide a tight and leak-resistant seal between the oil fill tube and the crankcase to reduce the possibility of oil leakage.
In addition, the axial flexing allowed by the extendable and contractable accordion section of the oil fill tube allows the oil fill tube to be selectively extended or contracted to accommodate a variety of differently sized engines, allowing a single oil fill tube to be manufactured which is compatible with a variety of differently sized engines, thereby reducing manufacturing costs.
In one form thereof, an internal combustion engine is provided, including a housing containing an oil sump and having a fill hole through which oil may be filled into the oil sump; an attachment member externally mounted on the housing; and an oil fill tube having an extendable and contractable accordion section intermediate first and second ends, the first end affixed to the fill hole in fluid communication with the oil sump with the oil fill tube attached to the attachment member.
In another form thereof, an internal combustion engine is provided, including a housing including a crankcase with a shroud attached thereto, the crankcase having an oil sump contained therein; an attachment member externally mounted on the shroud; and an oil fill tube retained by the attachment member, the oil fill tube including a first end attached to the crankcase in fluid communication with the oil sump and a second end through which oil may be filled into the oil sump, the oil fill tube capable of flexing axially to thereby aid in isolating relative motion between the shroud and the crankcase.